Question

Buffer Solution		pH after 1 drop		pH after 2 drops		pH after 3 drops		pH after 4 drops		ΔpH / drop
Buffer 1 + HCl		3.2		2.9		2.6		2.4		Try 1: ✘ 0.225 Try 2: ✔ 0.250 1.5 5
Buffer 2 + HCl		3.5		3.3		3.1		2.9		Try 1: ✔ 0.193 3 3
Buffer 3 + HCl		4.1		3.9		3.8		3.7		Try 1: ✔ 0.118 3 3
Buffer 4 + HCl		4.6		4.5		4.5		4.4		Try 1: ✔ 0.0600 5 5
Buffer 5 + NaOH		4.6		4.7		4.8		4.8		Try 1: ✘ 0.0650 Try 2: ✘ 0.0750 Try 3: ✘ 0.0660 Correct : ✔ 0.0400 0 5
Buffer 6 + NaOH		5.2		5.3		5.4		5.5		Try 1: ✔ 0.110 3 3
Buffer 7 + NaOH		6.0		7.1		10.7		11.1		Try 1: ✔ 1.36 3 3
Buffer 8 + NaOH		6.2		10.0		10.9		11.2		Try 1: ✔ 1.34 5 5

Which buffer is the best buffer? and why?

Answer 1

Buffer 4 and buffer 5 are the best buffers. Because in buffer 4 on the addition of HCl, there is only 0.2 pH change for 1 to four drops and the delta pH = 0.0600. In buffer 5, on the addition of a base, there is also 0.2 pH change corresponds to delta pH =0.0400. Both of them are very good buffers, one in acidic and one in basic medium.